1. Field of the Invention
This invention relates generally to a traction drive spindle device to be connected to main shafts of various machine tools and more particularly to such a device best suited for rotating a cutting tool of drive spindle device small diameters at a high speed.
2. Prior Art
In a conventional speed-up spindle of general types, a planetary gear mechanism is connected between an input shaft, connected to the main shaft of the machine, and a high-speed spindle (an output shaft) having a chuck attached to its front end. The speed of rotation of the input shaft is increased by the planetary gear mechanism so that the high-speed spindle rotates at a high speed.
Such a high-speed spindle device incorporating the planetary gear mechanism, however, has been found disadvantageous, in that the device is inferior in rigidity, and as a result, the device is liable to undergo vibration during the machining operation. Another problem is that the device can operate only under a relatively low load.